Ship&#39;s course and position indicator



Dec. 14 1926. 1,610,412

s. w. BALCH SHIPS COURSE AND POSITION INDICATOR Filed Nov. 1.3, 1922 5 Sheets-Sheet l Dec. 14 1926.

S. W. BALCH SHIPS COURSE AND POSITION INDICATOR 1922 5 Sheets-Sheet Filed Nov. 13

Dec. 14 1926.v 1,610,412

s. w. BALCH SHIPS COURSE AND POSITION INDICATOR Filed Nov. l5, 1922 5 Sheets-Sheet 5 Dec. 14 1926. 1,610,412

s. w. BALCH SHIPS COURSE AND POSITION'INDICATOR Filed Nov. 13, 1922 5 sne 4 Inventor,

Dec. 14 1926. 1,610,412

s. w. lBALCH SHIPS COURSE AND POSITION INDICATOR Filed Nov. 15, 1922 5 Sheets-sheet 5 Inventor Umrao STATES' -P-Af'rENr oF 1,610,412 FICE SAHUEL W. BALCH, 0F HONTCLAIR, NEW JERSEY.

SXIPS COURSE AND POSITIQN IDICATOR.

Appli-cation #led November 13, 191122.- Serial No. 600,547.

The object of this invention is to provide an instrument for use on shipboard by which the determination of position is facilitated when dead reckoning must be relied upon, and by which the direction is indicated which should be steered in order to follow the course of the great circle to the `destination. `Further objects are to provide an instrument which is adapted to a chart 0f suiiiciently large scale and yet which will take up but little space in the pilot house.

. The principle is such that all requisite adjustments are obvious and the construction is such that they are readily made so that mistakes are avoided and the information required for directing the vessel along the shortest course to the destination is given in a readily understood manner and so that it may be utilized with a minimum chance of error.

In the accompanying five sheets of drawings which form a part of this specification- Figure 1 is a front elevation of an instrument which embodies this invention, and

Fig. 2 is a plan view of the same.

Fig. 3 is an elevation of the automatic propelling means for the position indicator drawn to an enlarged scale,

Fig. 4 is a section through the same on the line IV-IV of Fig. 3, and

Fig. 5 is a section through the same on the line V-V of Fig. 3.

Fig. 6 is a vertical section through the frame of the instrument on the line V-VI of Fig. 1, all of the movable and adjustable parts being brought into a vertical plane.

Fig. 7 is an elevation of the indicating head of a taffrail log wherein is located the contacts of the electric circuit for actuating the instrument.

Fig. 8 is a plan of the gear train of the indicating head showing the contact springs, Fig. 9 is an elevation of the same, and

Fig. 10 is a sectional plan of the same on the line X-X of Fig. 9 showing the cam for closing the contacts and the escapement therefor.

Fig. 11 is a view of the ships log which is connected to the indicating head.

Fig. 12 is a plot of latitude and longitude lines included within an area of ten degrees to either side of a greatl circle which isY used as the axis of a chart t0 be used with the instrument. A

Fig. 13 is a chart adapted to be used with the instrument, based in part on the plot di the preceeding figure and in part on a plot of a continuation along the great circle axis thereof.

The instrument comprises a' chart support consisting of a frame 16 with .t cylindrically concave table 17 upon which a chart 18` may be supported. Under the table is -a great circle arc 19. in tlie axis of the concavity of the table is va ball-socket in tvio parts one of which 21 is carried by the frame and the other of which 22 is engaged by a clamping nut 23.` A vball 26 which is clamped in the socket has a projecting stem 27 to which an arm 28 is secured which is set so as to point to the vessels destination on the chart with respectto the great circle along which the navigator is undertaking to direct the vessel'. By destination, the port which is to be made is to be understood onlywhen a clear great circle course can be drawn through it from the position of the vessel. Where a course must be followed which is made up of two or more great circle coursesin order to avoid obstructions to navigation the destination as herein used may be the junction point of two such courses at which on being reached by the vessel the instrumentmust be reset. The connection between the arm and stem may be loosened at the wing nut 29 but the arm is preferably released for setting at the ball socket for it is then freed for setting in any direction. From the ball there is 'an oppositely projecting stem 31 on which is mounted an arm 32 for the support of suitable automatic propelling mechanism. This arm is clamped by la wing nut 33. The destination indicating arm, the ball with its stems and the arm with the propelling mechanism usually remain secured together and are operatively the destination lindicating member.

A bearing formed on one of the projecting stems from the ball carries a position indicating arm 34. The arm may have a pencil or en point 35 to make a pencil or ink mark as 1t traverses the chart and leave a permanent record thereon. In this case the point should be carried by a telescoping part 36 4so that it will reach and bear against' the chart and make a mark and the telescoping movement should be along a radius or line through the ball joint. This telescoping feature is also useful if the point is used only as an indicator for the position is more close ly indicated when the pointer touches the chart any permanent adjustment as to length which is correct ,for indicating near the middle of the chart will be too short for close indication near the side margins. The'Vl arm must be lengthened to reach any point of the chart on either side of the great circle of tangency. A toothed segment 57 having as its axis the bearing of the position Indicating'arm is an .integral part thereof, .the two. constituting the position indicating member.

The position indicating member is automatically moved toward the destination 1ndicating member proportionally to the speed of the vessel. The driving mechanism (Figs. 3, 4, and 5) includes a two-spool electromagnet 41 the poles of'which are bridged by a bearing plate 42 of nonmagnetlc material. Between and parallel with the poles of the magnet is an arbor 43 which is journalled in the bearing plate and the base plate of the electromagnet. Attached to this arbor are a single thread worm 44 and 'a fifteentooth ratchet 45. Loose on the arbor are an armature 46 and a pawl arm 47 which carries a pawl 48. The pin 49- 011 which the pawl is hingedis engaged between the two recur'ved ends of a torsion spring 51 andthe two ends also engage a lip 52 on a block 53l which is pivoted. to the bearing plate and carried thereby. The spring normally holds the pawl pin 49 opposite the lip52 and the armature out of alignment with the poles of the magnet. When the magnet is energized the armature is attracted into line'between the poles and the pawl is stopped by striking a shoulder 54 on the block so that the feed.

is limited to one tooth of the ratchet each time that the magnet is energized. The arts can be reversed to the positions indi.

cated by dotted lines in Figs. 4 and 5 and the direction of feed will then be reversed. The worm engages a worm wheel 55 with sixty teeth and a pinion 56 attached to-this wheel meshes with the toothed segment 57 which is attached to the position indicating arm. The tooth ratio between the pinion and segment is one to twenty-four. Each actuation of the electromagnet therefore moves the position indicating member through one minute of arc. The electromagnet is attached to its supporting arm in such a man n'er that it can be dropped to the position indicated by dotted lines in Figs. 4 and 6. This disengages the worm from the worm wheel for quick setting relatively to each other of the position and destination indicating members.l j

' The circuit through the electromagnet may be controlled by any instrumentality wh1ch moves proportionately to the speed of the vessel, as'for example a taifrail log 61. Ihis log through a line 62` connects with an indicating head 63 which. contains a gear train bywhich an arbor 64 is caused to make' one revolution to each nautical mile. Loosev on this arbor is a contact actuating cam 'V65 which engages one of two contact fingers 66 and 67. The cam is connected with the arbor through a spring 68. 'A pin 71 projects from its upper face and is engaged by one dog 72 of an anchor escapement. A pin 73 projects from its under face and is engaged -by the other dog 74 of the anchor escapement. The escapement is operated by an eccentric 75 on the arbor through an arm 76.

,The pins 'are so positioned in the cam that when the first mentioned pin is released itv will make nearly a complete revolution and during most of the time while it is moving under the impulse ofthe spring the contacts isire as'ed there is only a slight movement without closing the contacts. Hence the time during which the contacts are closed depends on the strength of the spring and the inertia of the cam and is therefore substantially uniform and independent of the speed ot' the log and there is no point at which the' log couldstop and leave the contacts closed. V'Vaste of electric current is thereby avoided. The log sends an electrical impulse to each revolution of the arbor 64,

area., essed together. When the other in f liu. e P

that is to say an impulse for each nautical v mile.

The instrument as shown admits a -chart which includes an area sixty degrees in length and twenty degrees in width. Limitation to these dimensions is not essential, but this is sufficient to includev almost any unbroken course on one chart. For a course which crosses the equator and is longer than sixty degrees a separate chart is used for each side of the equator. The size of the instrument is thereby kept down.

The chart is constructed-asa projection from a sphere to a cylinder tangent along a great circle which crosses the equator at some even ten degree angle and passes nearest to the course for which the'chart is pren pared. Such a great circle will be tangent member, and one of them, preferably the protractor to effect direct reading, is free to turn on the arm of the position indicating member. A wing piece 83 is carried by the protractor and is engaged by a pole locating guide 84. This is'a forked piece which is pivoted in a latitude arc support 8 5. The

For additional accuracy, a consupport is carried from the great circle arcV under the table, preferably through an exspherical surface.

tension arc 87 so as to permit a greater range of adjustment, as for example when 1t is necessary to carry the latitude arc .support from a position on the great circle which is not under the table as shown 1n Fig. 2. The pole locating guide is\so placed that if the chart were extended to` include pole of the chart would also pass through the pole guide. It is not *thought4 necessary to make either the latitude or great circle adjustments continuous and there is only provision for setting at even ten degree'intervals, for charts may be drawn so as to be suited to these adjustments yand made to include any course.

The radius of the chart support should correspond to the radius of the sphere on the same scale as the chart and will therefore be 636.18 millimeters.

In using the instrument a chart includin the course to be followed is placed upon the support and secured. The pole locating guide is positioned in line with the meridians of the chart. The destination indicating member is set on the port of ,destination if there is a clear course thereto. If the course is intercepted by a cape or other obstruction, then the destination indicatoris set at a safe distance ed such obstruction. The other `indicator is set on the present location of the vessel, the instrument is clamped and the electromagnet is connected with the log. The vessel is then steered as shown on the protractor the indication of which will be continually changing,

making the necessary allowances for mag-v netic variation, .drift and` current. As astronomical sights are taken or the position is otherwise ascertained the instrument is unclamped and reset.

It has been found possible to construct a vmap for consultation on a plane surface with ordinary drafting tools so that any two intersecting lines will be at the same angle on the map as on the earths surface. A Mercator projection is such a map and a straight line thereon is a rhumb course, but does not represent the shortest distance between two points. Also a map can be constructed representing a spherical surface on a plane so that any straight line on the map will designate the arc of a great circle on the sphere and the shortest distance between the points at the ends of the line on the If `projected from the sphere above defined a straight line between'any two'pointsv will indicate a course which will never deviate from the shortest course on the spheroid by more than a third, of a kilometer and will negligibly differ therefrom in length. .Also a map can be constructed, if limited to twenty degrees .m width, so that the difference in scale between the edges and the center will be linmed to one and one-half percent, But-each of these three maps involves a sacrifice of the desirableproperties of the other two. However, a chart constructed as above dened andconsulted with thelaidof this instrument will be found to have all of these desirable properties. By setting the two indicating members on any line the protractor will show the angle of such line with the meridian. If it is desired to rule a great circle line on the chart, the two indicating members are set at the'iends of the line and then the position indicating member is moved toward the other. If the distance is to be ascertained, the position indicating member is moved by turning the arbor 43 and counting the number of' revolutions, each revolution indicating fifteen nautical miles, and each tooth of the ratchet indicating one nautical mile.

I claim,

1. In a ships position indicator, a chart support, a chart, a destination indicating member universally adjustable with respect to the chart, a position indicating member, and automatic means for moving the position indicating member toward the destination indicating member proportionally to the distance traversed by the ship as shown on ythe chart.

both of which are universally adjustablel with respect to the chart, and automatic means for moving the position indicating member. toward the .destination indicating member proportionally to the distance traversed by the ship as shown on the chart.

3. In a ships position indicator, a concave chart support, a chart, a destination indicating member and a position indicating member both of which are universally adjustable with respect to the chart support about the center of the concavity, and automatic means for moving the position indicating member toward the destination indicating member proportionally to the distance traversed by the ship as shown on the chart.

4. In a ships position indicator, a cylinmember toward the destination indicating member proportionally to the distance' traversed by the ship as slmwn on the chart.

5. In a ships course and position indicator, a. chart support, a pole locating guide, a chart, a destination indicating member and a position indicating member both of which are universally adjustable with respect to the chart, anda protractor and an indicator therefor carried by the position indicating member one of which is connected to the pole locating guide.

6. In a ships course and position indicator, a chart support, a pole locating guide,

l a chart, a destination indicating member and a position indicating member both of which are universally adjustable With respect .to the chart, a protractor and an indicator therefor carried by the position indicating member one of which is connected to-the ole locating guide, and automatic -means or movlng the pos1t1on 1nd1cating member toward the destination indicating memberA proportionally to the distance/.traversed by the ship as shown on the chart. u 7. In a ships course' and position indicator, a concave chart support with a great circle arc, a pole locating guide, an arc supporti; for the pole locating guide with a latitude? arc along which the guide is adjustable, the arc support being adjustable along the great circle arc of the chart support, a chart, a destination indicating member and a position indicating member both of which are universally adjustable with respect to the chart support, and a protractor and an indicator therefor carried by the position indicating member one of which is connected to the pole locating guide.

SAMUEL W. BALCH. 

